Parallel plate busways for 600 volt (rms) systems often have high insulation failure rates when conditions are humid or wet. Most failures occur in joints between sections. A few occur in the sections between joints. Considerable damage to the loads and busway occurs when there is a failure, and down time is needed for repair. Presently, busway systems are tested off-line in an attempt to avoid sudden, unexpected, catastrophic failure. There is considerable expense and down time for periodic leakage resistance measurement (meggering) of the busway systems. Such insulation failures also occur in other types of insulated systems including transmission lines, switchgear equipment, motors, generators, transformers, capacitors, and inductors.
Partial discharge analysis is a common tool in monitoring high voltage motors and generators. Ultrasonic monitoring of exposed surfaces has been used to evaluate surface discharge conditions in motors and high voltage power lines. Chemical species detectors are widely used for safety monitoring. Additionally, as is well-known in the art, various kinds of apparatus commonly used in industry such as adjustable speed drives, and spot welders put energy into the same frequency range as the discharges that are being monitored. This can result in falsely predicting failure.